Significant advances in the use of monoclonal antibodies for the clinical analysis of routinely processed tissue are based upon the hypothesis that there exist antigen determinants in human tissues which are resistant to routine fixation and paraffin embedding which can be employed to identify types and subtypes of neoplasms. In order to test this hypothesis, we propose a novel approach for generating monoclonal antibodies reactive with formalin fixed, paraffin embedded tissues -- antibodies against antigenic determinants that are preserved during routine tissue processing. Mice and rats will be immunized with tissue which has been fixed, paraffin embedded and rehydrated, and hybridomas will be generated by fusion of their spleen cells with mouse or rat myeloma fusion partners. Antibodies will be screened and selected on the basis of immunoperoxidase staining of routinely fixed and processed paraffin sections. Results of an initial test fusion indicate that this approach will produce monoclonal antibodies which react with processing resistant or processing dependant determinants and which can be applied to routine paraffin sections for characterization and subsequent use in diagnostic pathology. After development and testing of this novel protocol in a model system employing normal kidney as immunogen, the method will be used to generate monoclonal antibodies reactive with renal cell carcinomas. Antibodies will be tested for their patterns of reactivity with tumor and tissue differentiation antigens, selecting for antibodies capable of: a) identifying the origin of a metastasis, b) distinguishing neoplasia from reactive processes or c) subclassifying histopathologically similar lesions. Antibodies will be tested extensively on panels of human neoplasms and normal tissues to determine their clinical utility. Since they will all be selected for the ability to react with paraffin embedded tissue, indepth characterization and critical analysis of antibody specificities can be performed through staining of tissue specimens selected from the entire experience of our surgical and anatomic pathology programs. These studies should lead to description of a panel of monoclonal antibodies capable of making significant contributions to the diagnosis and treatment of these important neoplasms. This novel approach to the generation and selection of monoclonal antibodies should permit isolation of antibodies of many specificities that are of general applicability and importance to the practice of pathology.